Radial engines more favored in Germany, 1935-45?

[WARSPITER]

The eventual Ford GAA had 100 more horsepower than the the wright radial in the Sherman and was more reliable.

 

[z42]

Smaller parts count should account for something on an engine that is bound to be made in many thousands in a country that has problems with securing a good deal of raw materials. Granted, a 9 cyl can work - perhaps short-stroke the BMW 132 or Bramo 323 (sorta "German Mercury"), down-rate it so it can use lower octane fuel and be done with that? A bespoke 7 or 9 cyl might be even better, or copy the Americans with the R-985 or 975? Or a bigger A-S Cheetah?

Cheetah is probably quite close to what's wanted, if we want a cheap and robust radial as a replacement for the Argus air cooled V-12. A down-rated 132 or 323 is probably a bit heavy, as they're considerably larger engines at close to or around 550 kg vs around 300 kg for the Argus, Cheetah and the R-985.

Liquid cooled engines were in theory better able to take advantage of the high octane fuel.

Interesting, any idea what is behind this effect?

Anyway, if so, one could argue from this perspective it would have made sense for Germany to focus more on air cooled engines than they historically did?

For the Germans, however it seems like the BMW 801 was no worse in this regard than the DB engines (German engines were not taking all of the advantage of the very high rich rating of the C3 fuel anyway, per British reports; C3 rich rating being noted as better than on the Allied 130 grade fuel as war progressed). Eg. the BMW 801C gained ~300 HP vs. 1943 801D, despite the increased CR of the 801D (compare with the small V-1710 making 700-800 HP more on 130 grade vs. 91 octane, but also against the DB 605 gaining ~200 HP, and the 601 being worse still). Engine is supposed to actually withstand the increased stress that over-boosting brings along.

Yes, German engineers were probably spending so much time trying to get their engines running reliably with their critical material shortages that they never were able to leverage their designs to take advantage of better fuels. So Germany is probably a poor example for studying the performance improvement from higher octane gasoline.

 

[Shortround6]

s for the small radial - making 30000+ of 7 cyl radials of 20L and 500-600 HP should've been easier on the German budget, manhours and raw material supply than making the same number of V12 air cooled engines.

The German air cooled V-12s used the same cylinders, heads, pistons and con rods (?) as the Hirth V-8s. They used the same cylinders, heads, pistons as Hirth $ and 6 cylinder engines.
The Argus V-8s used larger cylinders, which were very close to the size used in the Larger Walter engines. In fact they were almost identical to size of the Cylinders used in the DH Gypsy-major Series or the Blackburn Cirrus Major engines. The larger cylinders from whatever company (and we can include French and Italian versions) were 118-120 X 140 mm. The smaller cylinders were bit more varied but the Walther and Hirth engines used 105 X 115 cylinders.
The 500hp V-12 Renault used 120 X 140 cylinders.
The small V-12s were about 12 liters, the big V-8s were about 12.7 liters and the big V-12s were about 19 liters. Note that the high revving small V-12s were around the same power as the large V-12s (Renault and Gypsy King).

A simple, cheap robust radial engine for LW might've looked like the Ha 41/109 series by Nakajima, or as Kasei by Mitsubishi (perhaps even short-stroke Kasei so it is more compact) - each of these engines were very light when compared with BMW 801. No-nonsense engines, and were able to run on Japanese fuel that was in it's best day of 91-92 octane

Pick two, not three

Nobody made deliberately heavy engines. If you are making very light engines compared to the competition you are giving up something. Reliability or durability (not the same thing) or both. Or you just don't make as much power per pound/KG.

Using MW50 or GM-1 reduces engine life. It is not magic and has to be paid for somehow.

Octane.....................PN
87.............................68.29
91.............................75.68
96.............................87.50

The octane scale is a bit misleading when it comes to power potential.

 

[tomo pauk]

Interesting, any idea what is behind this effect?

It probably had a lot to do with water being better at removing the extra heat generated in small amount of time, than air it was capable for.

Anyway, if so, one could argue from this perspective it would have made sense for Germany to focus more on air cooled engines than they historically did?

There were certainly good places where to use them, while providing a back-up in case the very fancy 24 cyl liquid cooled engines flunked. Much like R-2800 was a cushion against the hi-per engines non-materializing (in sense of actually having them for service) in the USA.
We can again take a look at Japanese engines, too. Homare waslight, compact and powerful, while plagued by many problems beyond manufacturer's reach. The big Ha-42 making plenty of power on low-octane fuel. Japanese 14 cyl engines (bar the smallest ones, like Sakae and Zuisei) were also very powerful for the accompanying weight and bulk. BMW 801 was probably over-built, however.

Eg. a Ha 41/109 equivalent made in Germany. Will have fuel injection (+10% more power, give or take), excellent layout of exhaust stacks (Fw was already in 1938 depicting the individual exhaust stacks for the Fw 190 prototype - gain of 10 mph?), installed on Fw 190 means the cockpit stays where it was, and wing remains the same since Ha 41/109 was a light engine. Will also give better mileage. End result might be a working Fw 190 in service months before it was the case historically, and be in use in Russia and in Africa by early 1942 instead of in late '42.

 

[Shortround6]

Cheetah is probably quite close to what's wanted, if we want a cheap and robust radial as a replacement for the Argus air cooled V-12. A down-rated 132 or 323 is probably a bit heavy, as they're considerably larger engines at close to or around 550 kg vs around 300 kg for the Argus, Cheetah and the R-985.

The Cheetah is too small (13.7 liters). Also at 7 cylinders it may cause problems.

From the US you had the
Continental R-670 (10.9 L) 9 cylinders 240hp
Jacobs L-4 (12.4 L) 7 cylinder 245hp
Jacobs L-5 (13.6 L) 7 cylinder 285hp
Jacobs L-6 (15.0 L) 7 cylinder 330hp
Lycoming R-680 (11,1 L) 9 cylinder 300hp
P&W R-985 (16,1L) 9 cylinder 450hp
P&W R-1340 (22.0L) 9 cylinder 600hp
Wright R-760 (12.4 L) 7 cylinder 350hp
Wright R-975 (15.9L) 9 cylinder 450hp

and a fan favorite
Ranger V-770 (12,7L) inverted V-12 520hp which did ok (not great) in some twin engine trainers with BIG cowlings.

leaves out the under 200hp radials. Fuel vary from 73 (some the Jacobs) to 91 (P&W and Wrights) although they had versions that ran on lower octane at lower powers.
The Jacobs engines, especially the big one were known as "shakin' Jakes" from their vibration. Trading engine cost for airframe maintenance may not be good long term trade off.

For the US most of these engines date back to the late 20s and early 30s so the tooling was already in place and the engines were well known in civil aviation. There was no question of "designing" new trainer engines.

Yes, German engineers were probably spending so much time trying to get their engines running reliably with their critical material shortages that they never were able to leverage their designs to take advantage of better fuels. So Germany is probably a poor example for studying the performance improvement from higher octane gasoline.

 

[Admiral Beez]

What did Japan think of the BMW radial in the Fw 190?

Focke-Wulf FW 190 Evaluated by Japan - Destination's Journey

Photographs of the Focke-Wulf Fw 190A-5 received by the Japanese Army Air Force for evaluation purposes.

www.destinationsjourney.com

 

[Shortround6]

It probably had a lot to do with water being better at removing the extra heat generated in small amount of time, than air it was capable for.

In engine/fuel terms air cooled engines (high performance) were considered as "severe" duty engines. The air cooled engines were more prone to isolated hot spots in the cylinder heads while the water cooled engines averaged the temperatures better, not saying that were not hot spots. The Air cooled engines were running closer to the detonation limits.

Much like R-2800 was a cushion against the hi-per engines non-materializing (in sense of actually having them for service) in the USA.

Not sure about this. P&W was working on a large 18 in 1936 of 2600 cu in until they found out that the new Wright engine was a 2600. Being a bit later in timing P&W went to 2800 to "one up" Wright. Both companies had both civilian (airliner) and military sales in mind and knew that the commercial market was not interested in liquid cooled engines. Once it looked like Military sales might pick up both companies tried to come up with liquid cooled engines and in both companies the programs came to no useable hardware.

The big Ha-42 making plenty of power on low-octane fuel. Japanese 14 cyl engines (bar the smallest ones, like Sakae and Zuisei) were also very powerful for the accompanying weight and bulk. BMW 801 was probably over-built, however.

End result might be a working Fw 190 in service months before it was the case historically, and be in use in Russia and in Africa by early 1942 instead of in late '42.

The Germans have to come up with the similar size engine and then develop it faster than the Japanese did. The Engine in the Ki-44 II didn't show up the 2nd half of 1942 and was about 100hp down compared to the BMW 801D used the FW 190A-3 (?).
And again, what was the engine life like for the Japanese engines?

 

[tomo pauk]

Not sure about this. P&W was working on a large 18 in 1936 of 2600 cu in until they found out that the new Wright engine was a 2600. Being a bit later in timing P&W went to 2800 to "one up" Wright. Both companies had both civilian (airliner) and military sales in mind and knew that the commercial market was not interested in liquid cooled engines. Once it looked like Military sales might pick up both companies tried to come up with liquid cooled engines and in both companies the programs came to no useable hardware.

Let me reformulate.
R-2800 also ended up as an insurance vs. the hi-per engines over-promising and under-delivering.

The Germans have to come up with the similar size engine and then develop it faster than the Japanese did. The Engine in the Ki-44 II didn't show up the 2nd half of 1942 and was about 100hp down compared to the BMW 801D used the FW 190A-3 (?).

Hence this thread
The Ha 109 was without the fuel injection (German engine will have that feature, for a bit more power). Japanese were indeed slow with production of the Ha 109, even if not with designing it/modifying it from the Ha 41. In 1941, 12 were delivered, double digits were achieved in May of 1942, triple digits in Oct 1942 (table attached).

And again, what was the engine life like for the Japanese engines?

Compared with BMW 801s of 1941-42 - engine life was wonderful.

 

[z42]

In engine/fuel terms air cooled engines (high performance) were considered as "severe" duty engines. The air cooled engines were more prone to isolated hot spots in the cylinder heads while the water cooled engines averaged the temperatures better, not saying that were not hot spots.

So the argument for a liquid cooled engine benefiting more from an increase in octane vs. an air cooled, is that when/if these localized hot spots occur you're sort of screwed anyway and more octane doesn't help you develop more power? Whereas the liquid cooled engine with a more even head temperature distribution will be able to take advantage of the higher octane fuel?

 

[z42]

Compared with BMW 801s of 1941-42 - engine life was wonderful.

That's not setting the bar particularly high, is it?

 

[z42]

The eventual Ford GAA had 100 more horsepower than the the wright radial in the Sherman and was more reliable.

The two stroke Detroit Diesel twin 6-71 (6046) produced about as much power as the R-975, and the basic design was so good the 71 series remained in production until (per wiki) 1995.

(Though the twin setup was apparently a bit of a rush job, with some attendant issues, and was quickly replaced post-war by V variants).

 

[tomo pauk]

That's not setting the bar particularly high, is it?

Jokes aside, Japanese radials seem to be very reliable, with exceptions of the Mamoru (that one was quickly removed from production and service, representing less than 1% of Nakajima engines production from ww2), fancy versions (with extended prop shaft etc.) of Kasei, and eventually Homare (that was working fine when tested by the Allies, so probably the engine was okay).
Germans don't need to go with extended prop shafts for their radials, nor to push for a very light and compact 18 cyl engine - probably it is better to go conservative here; they also have some quantity of high oct fuel to help out, unlike the Japanese.

 

[Shortround6]

R-2800 also ended up as an insurance vs. the hi-per engines over-promising and under-delivering.

P&W was lead by Mead in the late 30s and unfortunately he drank of the sleeve valve cool-aid and started two liquid cooled 24 cylinder projects. They didn't do much with the smaller one but did make the larger one even bigger. Mead was in ill health by 1939/40 and Hobbs took over and pretty much canned the Sleeve valve project/s to concentrate on the air cooled engines. At the time of the cancelations the R-2800 was to some extend unproven engine of 1850hp, Testing was indicating more.
P&W had deleiverd the 5th R-2800 production engine in March of 1940. In May 1940 they started work on both the 2000hp B series and the 2100hp C series and in the summer of 1940 they were doing preliminary (Cylinder lay out studies) work on the R-4360. They authorized design work on the 3000hp 28 cylinder version Nov 11th 1940.

In 1940 nobody even had an idea of how badly the hi-per engines were going to flop. And the non-P&W hi-per engines used poppet valves.

 

[marathag]

Can we put a radial in Germany's tanks? No cooling system, though there is the Sherman-like height issue.

Radials don't have to be vertical.
or air cooled.

The Model B-9 was a nine cylinder water cooled horizontal radial type rated 140 hp at 1250 rpm
the total displacement was between 782 and 930 c.i. depending on source
They also made a larger D series, 2038 c.i. for 300hp and 990 pounds.

That was with WWI era metallurgy

Put the output shaft on the bottom for a low level driveshaft

 

[marathag]

the basic design was so good the 71 series remained in production until (per wiki) 1995

(in)famous for being known as Screaming Jimmys( GM ) from the high rpms they had to operate at, annoying/deafening to the Truckers that had them under the hood, and from the crankcases being pressurized to feed the cylinders, called 'Green Leakers' from the engine color and ability to mark its territory wherever they were parked.

But still awesome for overall power and durability. Emissions is what killed the GMC/Detroit Diesel. Just can't clean up a two-stroke enough. A very modular engine family in a variety of bore sizes and cylinder arrangements

 

[z42]

They were working on air cooled diesels, Porsche was working on the X-16 SLA 16, and Tatra had prototypes for air-cooled V-8 and V-12 diesels. AFAIU the motivation behind air cooling wasn't power/weight, but ruggedness, better tolerance for battle damage, and no issues with the coolant freezing in the Russian winter or boiling off in the African desert.

https://oldmachinepress.com/2018/02/05/sgp-sla-16-porsche-type-203-x-16-tank-engine/

Forgot to mention, this ruggedness of air cooling did come at a price. From the link above:

The first Sla 16 engine was tested in late 1944 and produced 770 hp (574 kW) at 2,200 rpm without the cooling fans. It took around 95 hp (71 kW) to drive the cooling fans, which reduced the engine's output to 685 hp (511 kW).

That's a quite staggeringly high fraction of the engine output being spent on turning the fans. I also heard somewhere the original VW Beetle with the air cooled engine used around 9 hp to drive the fan at full power. With 36 hp at the shaft, that's even a (very slightly) bigger fraction than the Sla 16.

Of course on a water cooled vehicle one also needs a fan pushing air through the radiator as well as a water pump. But those tend to require a substantially smaller fraction of the engine output.

 

[tomo pauk]

Bf 109H-4, deployed against Soviet Union starting from August 1941.
Powered by the BMW 809 ( ) engine - 36L, 750 kg, fuel injection, 1550 HP down low, 1330 HP at 5.7 km - and armed with four cannons. Praised for it's firepower and performance, as well as the wide-set undercarriage and good visibility.
(rotated the pic made by T. Mohr almost 60 years ago, denoting 2x MK 151/20 and 2x MGFFM)

 

[ThomasP]

A mini Wurger.

 

[ThomasP]

Wurger lite? hmmm

 

[ThomasP]

Now I am hungry.